<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<button id="btn1">1</button>
		<button class="btn2">2</button>
		<button name="btn3">3</button>
		<button>4</button>
		<button>5</button>
		<script type="text/javascript">
			var btn1 = document.getElementById("btn1");
			console.log(btn1.innerHTML);
			btn1.innerHTML = "<b>111</b>";
			
			var btn4 = document.querySelector(".btn2+button+button");
			console.log(btn4);
			
			var btn5 = document.getElementsByTagName("button")[4];
			console.log(btn5);
		</script>
		<input type="text" id="text" value="123">
		<script>
			console.log(document.getElementById("text").value)
		</script>
	</body>
</html>
